Diameter of Left Atrial Changes ??

I have an enlarged left atrium due, at least in part, to a history of a leaky mitral valve.  In July of 2007 the diameter was measured by echocardiogram at 5 cm.  The range for normal is given as 1.5 to 4.0.   The left atrium had been smaller in the echocardiogram about 3 years previous, and the leaky mitral valve was noted.  Prior to the July test, I had responded reasonably well to electrocardioversion to convert my AFig.  A couple of these lasted about 18 months each.  

I underwent open heart surgery in November of 2007 to repair the mitral valve.  Following healing I underwent another echocardiogram and the left atrium diameter was measured at 5.11 cm.  None the less, we tried a electrocardioversion in August of 2008 and it did not hold.  NSR lasted about on week.  

Then in August 2009 I underwent a follow-up check with an echocardiogram and the left atrium came in at 4.5 cm.  This was good news, but not a surprise to me as my surgeon said the mitral valve repair should result in some shrinkage of the enlarged left atrium.  I talked with my cardiologist about trying another electrocardioversion, and he said that seems reasonable, but wait another 6 months and again measure the atrium by echo.  That was done on March 25, 2010.  

Now the bad news, I think.  The left atrium measures the largest ever at 5.5 cm.  I have a follow-up appointment with my cardiologist and we will discuss this last test.

I know I have read somewhere, maybe on this community, that the measurement of the "diameter" of the atrium (or any chamber) is not very accurate - and thus, may I assume, may vary from test to test even if there is no change in the size?

[itdood]

Hi Jerry, I wouldn't read anything to it.

+/- 1 cm is within the margin of error for an echo.  I once researched the literature on this issue and there's much debate.

Some of the reasons why are:
The left atrium is very oddly shaped.  
The echo is attempting to guess the best area to measure, this will vary from scan to scan
The echo is trying to measure a moving target, it must scan at intervals then measure the largest interval which may or may not have been the maximum fill
The simple placement of the transceiver can vary this measurement (a.k.a we have the Human factor)

The human factor alone means there's going to be a lot of variation.

That's why the information can't be interpreted alone.  In and of itself it's a clue.  Then you team this up with other observations like blood pressure, stroke volumes, ejection fractions, wall motions, etc... to arrive at an educated guess most of the times.  :-)

Keep us posted on the follow up.  I'm really pulling for you to get back into NSR.  I know how much this means to you.

[Jerry_NJ]

Thanks for the explanation on the lack of accuracy.  The doctor who reviewed the echo commented "no significant change from 8/28/09, the one that gave a 4.5 cm reading.  

The interesting twist is my cardiologist who prescribed the echo did so at my request because I was encourage at the 4.5 cm reading.  He must have known that the next reading could be all the way back to the bad old "big" number.  Of course, he couldn't know without running the test.  The other good news is this test isn't a giant cost item, with Medicare discounts/allowed.